Rotary electric machine

Abstract

A rotary electrical machine includes a stator, a field core, a rotor, and first and second air gaps. The stator includes an AC coil that generates a rotating magnetic field with an alternating current. The field core includes a field coil excited by a direct current. The rotor is disposed on an outer circumference of a starting apparatus and held rotatably about a rotational axis relative to the stator and the field coil. The first air gap is formed between the stator and the rotor, and allows a magnetic flux to flow therebetween. The second air gap is formed between the field core and the rotor, and allows a magnetic flux to flow therebetween. The second air gap defines an interval extending along a direction that intersects an axial direction of the rotational axis on one end surface of the rotor in the axial direction of the rotational axis.

The invention claimed is: 
     
       1. A brushless field winding type rotary electrical machine disposed between an engine and a transmission along a rotational axis and positioned between a case housing a starting apparatus and the starting apparatus, comprising:
 a stator held by the case, the stator including therein an AC coil that generates a rotating magnetic field with an alternating current; 
 a field core held by the case, the field core including therein a field coil that is excited by a direct current; and 
 a rotor disposed on an outer circumference of the starting apparatus and held rotatably about the rotational axis relative to the stator and the field coil, wherein 
 a first air gap is formed between the stator and the rotor, the first air gap configured to allow a magnetic flux to flow between the stator and the rotor, 
 a second air gap is formed between the field core and the rotor, the second air gap configured to allow a magnetic flux to flow between the field core and the rotor, the second air gap configured to define an interval extending along a direction that intersects an axial direction of the rotational axis on one end surface of the rotor in the axial direction of the rotational axis 
 the rotor includes
 a first magnetic pole having a plurality of claw portions protruding from a first annular portion in the axial direction of the rotational axis, 
 a second magnetic pole having a plurality of protrusions that protrude in a radial direction and are arranged on an outer circumferential surface of a second annular portion at circumferential intervals in a circumferential direction thereof, the second annular portion disposed inside the first annular portion with a radial interval interposed between the second annular portion and the first annular portion and partially overlapping the first annular portion, and 
 a magnetic pole holding member with an annular shape having a fitting portion where the claw portions of the first magnetic pole and the protrusions of the second magnetic pole are fixedly fitted to each other, 
 
 each of the claw portions of the first magnetic pole is inserted into the interval between the protrusions of the second magnetic pole to alternately arrange the claw portion of the first magnetic pole and the protrusion of the second magnetic pole in the circumferential direction, and 
 the first magnetic pole and the second magnetic pole are fixedly fitted to the magnetic pole holding member without contacting each other. 
 
     
     
       2. The rotary electrical machine according to  claim 1 , wherein the second air gap is an interval extending along the radial direction on the one end surface of the rotor in the axial direction of the rotational axis, the radial direction being perpendicular to the axial direction of the rotational axis. 
     
     
       3. The rotary electrical machine according to  claim 1 , wherein the second air gap has an inclined portion that is an interval inclined from the axial direction of the rotational axis on the one end surface of the rotor in the axial direction of the rotational axis. 
     
     
       4. The rotary electrical machine according to  claim 3 , wherein the second air gap has the inclined portion inclined from the axial direction of the rotational axis and a perpendicular portion that extends continuously from the inclined portion and perpendicular to the rotational axis. 
     
     
       5. The rotary electrical machine according to  claim 3 , wherein an inclination angle of the inclined portion is in a range from 10 degrees to 25 degrees from the axial direction of the rotational axis. 
     
     
       6. The rotary electrical machine according to  claim 1 , wherein the field coil of the field core is disposed parallel to the rotor in the axial direction of the rotational axis with the second air gap. 
     
     
       7. The rotary electrical machine according to  claim 1 , wherein the first air gap is an interval that extends along the axial direction of the rotational axis on the one end surface of the rotor in the axial direction of the rotational axis. 
     
     
       8. The rotary electrical machine according to  claim 1 , wherein a first leading end locking portion of each of the claw portions of the first magnetic pole is fitted to the fitting portion disposed on an outer circumferential side of the magnetic pole holding member and fixedly held in the radial direction, and a second leading end locking portion of the second magnetic pole is fitted to the fitting portion of the magnetic pole holding member and fixedly held in the radial direction. 
     
     
       9. The rotary electrical machine according to  claim 1 , wherein the magnetic pole holding member is nonmagnetic. 
     
     
       10. The rotary electrical machine according to  claim 1 , wherein each of the first magnetic pole and the second magnetic pole is soft magnetic. 
     
     
       11. The rotary electrical machine according to  claim 1 , further comprising
 a permanent magnet disposed at a same circumferential position as each of the claw portions of the first magnetic pole is disposed, and on an inner diameter side of the first magnetic pole and an outer diameter side of the second annular portion of the second magnetic pole. 
 
     
     
       12. The rotary electrical machine according to  claim 11 , wherein the permanent magnet is a magnet primarily made of neodymium. 
     
     
       13. The rotary electrical machine according to  claim 11 , wherein the permanent magnet is a magnet primarily made of ferrite.